19f6cce4e3
(Recommit of r266002, with r266011, r266016, and not accidentally including an extra unused/uninitialized element in LibcallRoutineNames) AtomicExpandPass can now lower atomic load, atomic store, atomicrmw, and cmpxchg instructions to __atomic_* library calls, when the target doesn't support atomics of a given size. This is the first step towards moving all atomic lowering from clang into llvm. When all is done, the behavior of __sync_* builtins, __atomic_* builtins, and C11 atomics will be unified. Previously LLVM would pass everything through to the ISelLowering code. There, unsupported atomic instructions would turn into __sync_* library calls. Because of that behavior, Clang currently avoids emitting llvm IR atomic instructions when this would happen, and emits __atomic_* library functions itself, in the frontend. This change makes LLVM able to emit __atomic_* libcalls, and thus will eventually allow clang to depend on LLVM to do the right thing. It is advantageous to do the new lowering to atomic libcalls in AtomicExpandPass, before ISel time, because it's important that all atomic operations for a given size either lower to __atomic_* libcalls (which may use locks), or native instructions which won't. No mixing and matching. At the moment, this code is enabled only for SPARC, as a demonstration. The next commit will expand support to all of the other targets. Differential Revision: http://reviews.llvm.org/D18200 llvm-svn: 266115 |
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| CODE_OWNERS.TXT | ||
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| LICENSE.TXT | ||
| LLVMBuild.txt | ||
| README.txt | ||
| configure | ||
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README.txt
Low Level Virtual Machine (LLVM) ================================ This directory and its subdirectories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments. LLVM is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. Please see the documentation provided in docs/ for further assistance with LLVM, and in particular docs/GettingStarted.rst for getting started with LLVM and docs/README.txt for an overview of LLVM's documentation setup. If you are writing a package for LLVM, see docs/Packaging.rst for our suggestions.